Vacuum relief valve



Feb. 9, 1943. LARSON 2,310,447

VACUUM RELIEF VALVE Filed Feb. 20, 1942 J 'fZ//W Jawa Zcflla 7 507 Patented Feb. 9, 1943 umrso QSTATBS. t PA NT- OFi-iCB a auaur Donald E. Larson. Chicago. 111., alalgnorto can. eagogridge & IronOompany,acorporatlonof 1mm v Application February 20, 1942, Serial No. 431,629

This invention relates improvements in relief valves and more especially a valve adapted for use on aypressure container, for example, a storage tank containing gas or volatile liquid.

The relief valve is adapted for use as either a vacuum relief valve or a pressure relief valve: and it is to be understood that in speaking of pressure or excess pressure I mean either positive or negative pressure. Merely by way of example, I have here shown the invention applied to a vacuum relief valve.

In relief valves it is customary to provide a pallet or disk over the vent opening, said disk adapted normally to be unseated by a predetermined pressure in the container. It has been found, however, that occasionally such a disk anally be lifted whenever the predetermined pres- "sure for venting is reached in the container.

Above the disk It I provided a disk It carried on one end of the lever II which is pivoted at ll. The other end of the lever it is provided with a weight II. The disk It is sealed to the opening I 6 by flexible fabric I. so that upward and downward movement is permitted. The opening II is also inthe vent-pipe It sothat the disk i4 isalsoexposed to the internal pressure in the container it. The weight i! is so set that the disk It will not move unless there is pressure in the container in excess of the predetermined pressure adapted for normally unseating the disk it. For example. if the disk It is adapted to be unseated by negative pressure in the container of. say. 4 oz. under,

becomes stuck as a result of freezing or adhesion, or from other causes so that the predetermined pressure will not release it. This is more likely to happen, of course, in cases where the valve has not been operated for some length of time. Serious damage may result in cases where such a valve becomes stuck. The principal feature of my invention is the provision of means for forcibly unseating the valve in case it should become stuck. Such means are adapted to be operated by pressure in the container in excess of the predetermined pressure suitable for normal operation. For example, a vacuum relief valve may be made for normal operation at a predetermined pressure and the means for forcibly unseating it or kicking it loose in the event it becomes stuck may be adapted to operate at a pressure, say, 1 oz. higher than the normal operating pressure. In the case of a vacuum relief valve, of course, this would mean 1 oz. higher negative pressure or 1 oz. less positive pressure. Other features and advantages will appear more fully as I proceed with the specification.

In that form of device embodying the features of my invention, illustrated in the accompanying drawing,Flgure iisatopplanviewiand Fisurez is a vertical sectional view taken as indicated by the line I of Figure i.

As shown in the drawing, Ill may indicate the roof of a pressure container having a vent pipe Ii connected to a casing lid with the vent opening I2. .13 indicates a disk over the opening adapted normally to be unseated by a predeteratmospheric, the disk it may be adapted to be i moved by negative pressure in the container of 5 oz. under atmospheric.

2t, 28 indicate a pair of lever with their lower ends connected to the rotatable shaft 2|. The upper ends of the levers are connected by the strap 22. 28 indicates a'weight. The shaft 2! extends through the flange surrounding the vent opening it. This shaft carries a cam 25 adapted to strike the lug 28 on the disk It when the shaft 25 is rotated. The weight 23 is normally somewhat oif center as shown in Figure 2, but locked against falling by the catch 27 on the extreme and of the lever it beyond the disk It. when the disk it is pulled down, the catch 21 is released from the cross bar 22, permitting-the weight it to descend, thereby rotating the shaft 2!, causing the cam 25 to engage the lug 28 on the disk It with great pressure and thereby forcibly unseating said disk against any sticking caused by freezing, adhesion or otherwise.

After the disk It has been thus unseated by the weight 28, the parts must be reset by hand. The shaft II is also provided with a depending arm 20 carrying a signal flag 29 that israised when the weight 23 descends, to indicate visually to an attendant that the valve requires reseating.

It is to be noted that the lever arms 20, 20 really serve two functions for the catch 21 may be released manually and the weight. 23 lowered by hand to see whether the disk It is operating properly.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of marry modifications. Changes, therefore, in the construction and arrangement may be made without departing from thespirit and scope of the'invention as disclosed tion to claim all novelty inherent in my invention as broadly as permissible, in view of the prior art.

What I claim as new, and desire to secure by Letters Patent, ls:

1. A vacuum relief valve, including: a casing with a vent opening to atmosphere; an inwardly opening disk for closing said vent adapted normally to be unseated when a predetermined subatmospheric pressure exists in said caslns: a cam mounted on the casing adapted to be rotated to engage a part on the disk to unseat the same; means tending to rotate the cam; means normally holding the cam against rotation; and means operated by atmospheric pressure when the pressure-in said casing reaches said predetermined sub-atmospheric pressure for releasina' said holdin; means, whereby said cam will rotate and unseat the disk.

2. Apparatus as claimed in claim 1 in which the means for forcibly unseating the disk includes a movable diaphragm exposed to pressure in the casing on one side and to atmospheric pressure on the other side.

DONALD E. LARSON. 

